Electrical trolling motors are often used on fishing boats such as bass boats for quiet, low speed propulsion in fishing areas such as coves and inlets of lakes where the more powerful and noisier gasoline motor would tend to scare the fish away. The trolling motors are commonly powered by rechargeable batteries similar to automobile batteries. Often, two 12 volt batteries connected in series are employed to provide low speed power using one battery and a higher speed with the two batteries providing 24 volts. While it is desirable to connect the batteries in series for operation of the trolling motor, it is desirable to charge the batteries separately or to connect the batteries in parallel for recharging, for two reasons. First, when series connected batteries are charged, usually either the weaker battery is undercharged or the stronger battery is overcharged. Second, 12 volt battery charging devices are commonly available for recharging automobile batteries while 24 volt chargers are not as common and are, therefore, more expensive.
It is generally not desirable to manually disconnect the trolling motor or trolling motor control from the battery terminals, to connect the charger to each battery separately or to the parallel combination, and then reconnect the batteries in series to the motor. Such operations are laborious and unsafe if a wiring mistake is made which could result in damage to the batteries and the charger or injury to the boater or fisherman.
To prevent such problems, switching arrangements have been developed which connect the batteries in series for motor use and in parallel for charging. The known switching arrangements have employed manually operated switches, relays, and solid state switching components to accomplish the switching functions. While such switching arrangements have generally been successful in facilitating the proper interconnection of batteries for motor use and recharging, they are also relatively expensive. Since the environments which boats with such motors are exposed to run the entire range of cold, hot, wet and dry, the switching components must be carefully sealed to prevent corrosion of the switch and relay contacts and ensuing malfunction thereof. This adds to the expense of such arrangements.
Since trolling motors are typically operated at low voltages provided by batteries, the current drawn by them for a given power output is high. In addition, trolling motors have been found to be "voltage sensitive" in that small increases in series resistance between the batteries and the motor results in noticeable decreases in performance. For these reasons, the wiring for such motors is required to be of a heavy gage to handle the high current and to avoid adding resistance. The gage of the wiring is not a problem in itself. However, a problem of expense occurs in obtaining power connectors to handle the high current and heavy gages of wire needed. Commonly available and, thus, relatively inexpensive connectors are usually only rated for 20 Amperes maximum current. Such plugs and receptacles are usually designed for single connections of No. 8 to No. 10 AWG (American Wire Gage) sized conductors with no convenient provision for interconnections among the contact portions of the connectors. In battery operated trolling motors, it is desirable to provide a rated 45 Ampere capacity and employ No. 2 or No. 6 AWG sized conductors to lower the series resistance. However, there is a considerable cost leap to such higher rated connectors since such connectors are seldom used in consumer oriented products.